The present invention relates to a personal transportation system. In particular, it relates to an autonomous transportation system for people and light freight.
Transportation plays an important role in civilization. Nowadays, many cities around the world are facing serious transportation problems, in particular, traffic gridlock and air pollution from automobile use. There are many studies on the traffic problems and potential solutions, for example, Stuck In Traffic: Coping With Peak-hour Traffic Congestion by Anthony Downs, The Brookings Institution, 1992, and Breaking Gridlock by Jim Motavalli, Sierra club books, 2001. A salient feature of today's city traffic is that travel origins and destinations have become increasingly dispersed, varied and distant. Accordingly, automobile becomes the dominant form of transportation due to its convenience. In the United States, automobile accounts for 90% of passenger transportation and 90% of people drive alone. The heavy dependence on automobile also leads to traffic gridlock, air pollution, traffic accidents, and the dependence on fossil energy. Although there are progress in fuel efficiency, efforts to increase the highway capacity seem to be difficult. In areas experiencing traffic congestion, it is very expensive to construct new highways and purchase the rights-of-way. The National Automated Highway System or Intelligent transportation systems in the United States attempts to increase highway capacity by embedding sensors on the roadway and automated control of vehicles in short following distances on dedicated lanes. However, considerable infrastructure cost and liability issues pose serious doubts on this approach (Transportation Research Board Special Report 253, National Academy of Sciences, 1998). In addition, automobile is not readily accessible to school children and the elderly, a large fraction of the population. On the other hand, existing public mass transportation systems such as subway, monorail, light rail and bus systems are less favored than automobile in terms of convenience and comfort. As urban and suburban traffic becomes more dispersed, it is difficult to maintain the high volume necessary to justify the high construction and operation cost. The frequent stops of the vehicles and the transfers needed for many destinations make trips lengthy and uncomfortable, even for cities with well-developed public transportation systems.
The limitations of existing transportation systems and the need for new ideas have long been recognized. In 1968, US Department of Housing and Urban Development published a report Tomorrow's Transportation: New Systems for the Urban Future. One concept to provide accessibility and service to the profusion of origins and destinations in metropolitan areas is “personal rapid transit”, automated small personal vehicles on a network of exclusive guideways. It is originally proposed as a public transit system for areas of medium to low population density. The origin of the concept can even trace back to inventors as early as 1953 (See J. E. Anderson, Some Lessons From the History of Personal Rapid Transit, 1996). A demonstration project at Morgantown, West Virginia was funded, completed, and has been in continuous operation since 1975. Except for the vehicle size larger than current definition, the project demonstrated the basic features of a personal rapid transit system: 1) Fully automated vehicles capable of operation without human drivers. 2) Exclusive guideway. 3) Small vehicles. 4) Small guideways that can be located above ground, at ground level or underground. 5) Vehicles able to use all guideways and stations on a fully coupled network. 6) Direct origin to destination service, without a necessity to transfer or stop at intervening stations. 7) Service available on demand rather than on fixed schedules. Activities in other countries include Cabtrack in the United Kingdom, CVS in Japan, Cabinentaxi in Germany, Aramis in France. There are some recent systems, such as Taxi 2000 and its modification PRT 2000, and SkyTran in the United States, ULTRA in the United Kingdom, and RUF in Denmark.
The personal rapid transit concept offers some desirable features, but these systems have not been accepted for widespread implementation. Critical questions have been raised about the economical feasibility of the concept. See, for example, V. R. Vuchic, Personal Rapid Transit: An Unrealistic System, Urban Transport International (Paris), No 7, 1996, page 35. It seems to be mutually incompatible between the small size vehicles for low density travel and the substantial infrastructure investment for guideways, stations and sophisticated automation justifiable only for heavy traffic volumes. This is a reasonable argument in consideration of the costs of existing guideway systems such as subway, rail and monorail, and some previous personal rapid transit systems suffered from the dilemma. Attempts to increase the capacity by short headways of less than one second may face safety concerns similar to those of the automated highway system.
The criteria for the practical feasibility of a new transportation system may include: 1) Convenience and comfort. 2) Appropriate capacity. 3) Cost-effective. 4) Fuel efficiency, additional emphasis due to energy shortage. 5) Environment-friendly, air pollution, noise, aesthetic structure. 6) Safety, accident, theft, disease, weather. The traffic problems in urban and suburban areas cannot be adequately addressed by addition and improvement of existing transportation systems alone. New transportation systems are needed, and the new systems must demonstrate their feasibility against the above criteria.